Electrolytic cell



Oct. '20, 1942- H. WATERMAN 2,299,657

ELECTROLIG CELL Filed Oct. 25, `3.939

INVENTOR ATTORNEYS Patented Oct. 20, 1942 ELECTROLYTIC CELL Herbert Waterman, Ne

wBedford, Mass., assignor to Aerovox Corporation,

New Bedford, Mass., a

.corporation of New York Application October 25, 1939, Serial No. 301,181

2 claims.

The present invention relates to electrolytic cells, more especially to electrolytic condensers.

Among the objects of the invention are to provide an electrolytic condenser of compact and rugged structure and yet obviating the use of the relatively expensive, refined aluminum foil and the processing of such foil for increased surface area.

According to the invention the structure of the formed electrode or electrodes is a capillary body of film forming metal ordinarily of aluminum, which presents a tremendous internal capillary area that is film formed and also readily impregnated with electrolyte.

In the accompanying drawing in which are shown one or more of the various possible embodiments of the several features of the invention,

Fig. 1 is a view in longitudinal cross-section of one embodiment of the invention,

Fig. 2 is a perspective view of the riser head with the wires therein,

Fig. 3 is a fragmentary view in longitudinal cross-section indicating an alternative structure of anode mount,

Fig. 4 is a perspective view of the riser of Fig. 3 prior to application of the wire structure,

Fig. 5 is a fragmentary sectional view on a greatly enlarged scale illustrating the method of connection of the wires to the riser head in the embodiment of Fig. 3, and taken on line 5 5 of Fig. 4,

Fig. 6 is a side elevation of the anode and riser structure of a further embodimen.

Fig. 7 is a more or less diagrammatic crosssectionval view illustrating the method of producing the anode structure shown in the embodiment of Fig. 6,

Fig. 8 is a view in longitudinal cross-section of a further construction of anode,

Fig. 9 is a view in longitudinal cross-section of an alternative form of condenser structure, and

Fig. 10 is a view similar to Fig. 9 of another embodiment thereof.

Referring now to Figs. 1 and 2 of the drawing there is shown an electrolytic condenser of the wet typeillustratively comprising a cylindrical can II with a suitably vented closure l2 of any appropriate construction at one end thereof and `an insulating mounting structure, illustratively with a screw nipple I3 at the opposite end. The condenser can and its mount. are not per se claimed herein. Any known construction illusi allel wires aluminum.

tratively that of the prior patent to H. E'. Rhodes No. 2,163,262, of June 20, `1939, will serve.

The invention in the aspect pertinent to the present embodiment is concerned with the anode structure. In the embodiment shown, the anode consists of a capillary structure, in this particular embodiment a bundle B of fine generally par- I4 of lm forming metal, ordinarily The wire bundle and its `constituent wires are film-formed. The area of film is the combined surface area of the multiplicity of wires making up the bundle B. The film is thus of tremendous area for a given volume and therefore affords a correspondingly tremendous capacity. The individual wires I4 in the present embodiment are desirably aluminum, soldered to an aluminum riser plate I5, the rod-like end i6 of which extends through the closure plug I-3 for terminal connection.

Preferably a body of molded resin such as Bakelite, completelyembeds the riser plate I5 and the associated ends of the wires I4 and desirably also is molded as a unit with the screw mount I3 as shown in the drawings. Ordinarily the end of the riser rod I6 will be permitted to protrude from the molded plug I3 as shown in dash lines at Il and is subsequently headed over as at I8 for attachment of the terminal lug I9. Desirably an insulating liner sleeve 20 perforated as at 2| is disposed within the can and prevents any short circuiting tendency.

The electrolyte 22 may be of type conventional in so-called wet electrolytic condensers, ordinarily an aqueous solution of boric acid and sodium borate and it completely submerges the anode wire bundle B as shown. The capillary nature of the wire unit permits the electrolyte readily to impregnate the brush structure thereof and to come into intimate engagement with the surfaces of the individual bristles or wires, so that the full capacity com-es into play. If desired the can II which serves as a cathode may be of etched material for enhanced cathode surface.

By reason of the very high capacity per unit volume attained with the use of the anode structure set forth, -it will be seen that for a condenser of given capacity and given length the diameter may be reduced as compared with conventional constructions. Accordingly the distance from a wire at the center of the bundle to the inner surface of the can is not more than and in fact slightly less than half the internal diameter of the can. The major portion of the formed wire surface is near the outer peripheryof the In the embodiments of Figs. 3 to 5, the anode riser has a deeply gridded head 25 lodging the I ends of the individual bundles 26 of aluminum wires the said riser head being swaged together for securely retaining such wires in mechanical and electrical contact with the plate.

end of the riser headfhas a multiplicity of relatively deep sockets 21 in each of which a small bundle 26 of the wires is mounted and affixed, by swaging the head. As shown in this embodiment the riser head is provided with the unitary rod 28 about which is slipped and afxed in conventional manner the insulating mounting plug In the embodiment of Fig. 6 the anode is shown with an aluminum riser head 30 having as integral parts thereof, the bundle 3l of substantially parallel aluminum wires. The anode of Fig. 6 is made bythe method diagrammatically indicated in Fig. 7. As shown in this embodiment a plunger 32 mounting a slug 33 of aluminum of thickness greater than the riser head pushes the latter through a hardened die 34 having minute perforations 35 therethrough of diameter corresponding to that of the wire to be extruded. The plunger 32 has a depression 36 corresponding to the head 36 and associated riser rod 31. Ac` cordingly, under hydraulic pressure a part of the thickness of the slug v3.7i will be extruded to form the Wires 3l and the residual slug will be shaped to form the head 39 and rod 31.

In the embodiment of Fig. 8, aluminum wool of the character described in Ohmann Berichte, volume 45, page 2973 (1912), is employed. This wool is in physical appearance generally similar to steel wool lwhich is a familiar article of commerce. The aluminum wool is of lrelatively fine texture and is packed into a bundle 40 retained by the inwardly crimped rim 4| of a cup-shaped clamp 42 formed integral with the riser rod 43. The wire wool is lm formed land may be used in place of the structures shown in Figs. 1 to 6 inclusive.

In Figs. 9 and 10 are shown embodiments in which instead of resort to filaments of metal for building up the capillary electrode structure, the film forming metal is in the form of a block of sponge aluminum or other film forming metal. Sponge aluminum may be produced by any of a variety of familiar procedures known to those skilled in the art. Among the methods of producing it are the absorption of large volumes of gas under pressure by liquefied aluminum followed by the sudden release of pressure just prior to solidication. Alternatively aluminum gran- As best- A shown in the exaggerated view of Figi 5, the grid stream through the sponge aluminum, complete' ly to impregnate the interstices thereof and to eject any air therefrom.

In the embodiment of Fig. 9 the sponge aluminum block 45 made by any of the methods disclosed, is lodged with little or no clearance in a metal container 46 preferably lined as at 41 in manner similar to the showing 'of Fig. 1. A ter- `minal stud 4B at the otherwise free surface of the anode block is in effective contact therewith as for instance by a head 49 and protrudes through the insulating cover 5U, over which the rim 5l of the container 46 is crimped. The anode block impregnated with electrolyte as described substantially lls the container 46 all of the interstices of which are desirably charged with electrolyte. Y

The embodiment of Fig. 10 is particularly suitable on alternating current. Here both electrodes 52 and 53 are formed blocks of capillary aluminum such as shown in Fig. 9. Interposed between these blocks is a layer 54 of porous insulating material which is impregnated with electrolyte as are the two aluminum blocks. Terminals 55 and 56 are connected to the respective blocks and protrude through an insulating casing 51 preferably molded about the contents.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not -in a limiting sense.

Having thus described'vmy invention, what I claim. as new and desire' to secure by Letters Patent is:

1. An anode unit for an electrolytic cell comprising a multiplicity of substantially parallel fine aluminum wires, presentingv a capillary bundle, each wire having a lm coating thereon, analul minum riser head to which' electrical contact with one end of the bundle is made, and a molded resin block embedding the contiguous ends of the wire bundle and the head.

2. An anode for electrolytic condensers comprising a riser head of aluminum with a grid bottom, a bundle of ne aluminum wire, the ends of which are lodged and swaged in the depressions making up said grid for secure mechanical and electrical connection with the riser, the individual Wires having lm'formation thereon and the bundle presenting a capillary structure and'being adapted to be impregnated by electrolyte.

nnRaERT WATERMAN. 

